[libcxx-commits] [libcxx] [libc++] Save duration/timeout locally for condition_variable waits (PR #148330)

[John Sheu via libcxx-commits]

johnsheu wrote:

The relevant lines in the `std::condition_variable_any` implementation are highlighted here:

```c++
  template <class _Lock, class _Clock, class _Duration>
  _LIBCPP_HIDE_FROM_ABI cv_status wait_until(_Lock& __lock, const chrono::time_point<_Clock, _Duration>& __t) {
    shared_ptr<mutex> __mut = __mut_;
    unique_lock<mutex> __lk(*__mut);

    // User-supplied lock is unlocked here
    __unlock_guard<_Lock> __unlock(__lock);
    lock_guard<unique_lock<mutex> > __lx(__lk, adopt_lock_t());

    // User-supplied reference parameter is used here; bad news if it was protected by the above lock
    return __cv_.wait_until(__lk, __t);
  } // __mut_.unlock(), __lock.lock()
```

https://github.com/llvm/llvm-project/pull/148330